A standard waste-heat boiler has walls of with cooling-tube sections through which a coolant flows at a temperature T1. The waste gas flowing through the boiler is thus cooled by the cooling-tube sections through which the coolant flows. The cooling-tube sections are generally each formed by a plurality of cooling tubes that run along the boiler walls. It is within the scope of the invention that these cooling tubes form the inner wall of the boiler.
Waste-heat boilers of this type are known in various embodiments from practice. During operation they are under a production-side superatmospheric pressure so that deformations or buckling of the boiler walls would result if no suitable countermeasures were taken. Under unfavorable conditions, upstream subatmospheric pressures also occur that have to be taken into consideration in the boiler design. In practice, the cited pressures cannot be absorbed by the walls of the waste-heat boiler alone. Therefore, the boiler walls are supported by braces bearing against the boiler walls. These braces are generally rolled steel profiles whose dimensions are determined by influencing variables such as gas pressure, spacing of the shapes and size of the areas to be cooled. In the case of waste-heat boilers with small outer dimensions and corresponding boiler geometry, the forces acting as a result of gas pressure can generally be absorbed and compensated by a brace system surrounding the boiler on the outside. To this end an exchange of forces takes place here inside the brace system and further system parts to transfer the forces are not normally necessary. In the case of larger outer dimensions of the boiler and/or if lower, funnel-shaped particle extractors are present, a continuous brace system for the respective boiler is no longer possible. Here discontinuous braces are provided and the acting forces are transmitted via these braces directly or indirectly via so-called cold braces into a cold steel construction surrounding the boiler. It must be thereby in particular be assured that thermal expansion of the boiler is not obstructed. With these systems, the force absorption or the equalization of forces thus takes place outside the brace system. Of course, the steel construction has to be designed for the acting gas pressures and the forces to be absorbed due to the gas pressure can amount to up to several hundred tons. This makes extremely complex steel constructions necessary.